If you have a lump in the back of your knee you may have been diagnosed with a Baker’s Cyst. A Baker’s Cyst is also a called a popliteal cyst. A Baker’s Cyst typically forms when the knee is suffering from degenerative joint disease, meniscus injury or tear, and onset osteoarthritis. What causes the cyst to form is the accumulation or overproduction of synovial fluid.
A Baker’s Cyst can be a very confusing knee ailment for patients. First, it has nothing to do with being a baker, but rather it was named for the surgeon who first described it, Dr. William Baker. Second, it is often not explained by the attending physician that the Baker’s Cyst itself is not the cause of the patient’s knee problems, but rather a symptom of other pathology, most often arising from the anterior or front portion of the knee, not the back where it is found. Many people walk around with a Baker Cyst and remain asymptomatic. It is typically the other knee problems that will cause knee pain to eventual cause pain. The cyst itself can grow in size and compress the whole knee joint and cause stiffness, pain and discomfort. The Baker’s cyst, as being part of the symptomology of the knee, may be aspirated to relive symptoms, but as we will see the cyst often returns because the problem causing the cyst has not be resolved.
However, unless the front of the knee is healed by regenerative medicine injections the cyst will often return.
The bigger the cyst the worse condition the knee is in.
One of the reasons a Baker’s cyst will return after aspiration is that the knee is in a worsening degenerative condition. An October 2021 paper (1) investigated the factors affecting Baker’s cyst volume in young and middle-aged patients. The researchers found that the bigger the cyst, the more likely that the patient was suffering from a more advance cartilage degenerative situation of injury.
Treatment guidelines for Baker’s Cyst
Many doctors realize that it is the knee degeneration causing the cyst and follow the traditional, conservative care protocol. This includes:
- Rest/activity modification.
- Physical therapy. The physical therapy typically does not focus on the cyst but rather the degenerative problems, such as a meniscus tear that is causing the cyst to develop.
- Draining the cyst
- Corticosteroid injection
An April 2021 paper (2) recommends these treatment guidelines: “Baker’s cyst accompanying knee osteoarthritis represents a common cause of knee pain presenting to the emergency department . . . Baker’s cyst aspiration with corticosteroid injection represents a safe alternative treatment option for patients. In some cases, this treatment may be definitive (it cures the problem and there is no recurrence). Orthopedists currently use this procedure to reduce pain and improve function for patients with chronic knee ailments related to baker’s cysts.”
An August 2021 paper (3) suggested that Baker’s Cyst alleviation can be achieved short-term, but if the accompanying knee osteoarthritis progresses, treating the Baker’s Cyst will become significantly less effective.
“Several symptoms are common to knee osteoarthritis and Baker’s cyst. To what extent each condition contributes to the patient’s discomfort is still a matter of debate.” The researchers of this study wanted to first, compare the burden of symptoms in patients with isolated knee osteoarthritis and patients with knee osteoarthritis associated with Baker’s cyst; second, to assess the outcomes after conservative treatments.
- One-hundred and thirty patients were included in the study (97 with isolated knee osteoarthritis, 33 with knee osteoarthritis and Baker’s cyst).
- The study’s results shows that Baker’s cysts associated with knee osteoarthritis contribute to the burden of symptoms. The conservative treatment of both conditions allows significant improvements, but in the medium term (6 months) the effectiveness of conservative treatment declines in patients with knee osteoarthritis associated with Baker’s cyst.
Aspiration and cortisone injection for a ruptured Baker’s Cyst
Aspiration and cortisone injection for a ruptured Baker’s Cyst. In November 2020, (4) doctors suggested the effectiveness and safety of ultrasonographic guided aspiration performed with corticosteroid injection for ruptured Baker cysts.
The study included 42 patients with knee joint disorder associated with ruptured ruptured Baker cysts who were treated by ultrasonographic guided aspiration of fluid from the cyst and different points from the calf then intra-lesional injection of corticosteroids once or twice, one week apart. The patients were followed up weekly until a complete resolution of symptoms was attained. According to the doctors symptoms and knee function improved significantly in all patients at both post injection evaluation visits (1 week and 12 weeks). Ultrasonographic features improved significantly with complete disappearance of free fluid in the calf in 35 (83.3%) cases one week after the injection, and in 41 (97.6%) after 12 weeks. In regard to Baker cysts only 4 (9.5%) cases showed complete disappearance after 1 week and there was recurrent Baker’s cysts in 38 (90.5%) cases which required reaspiration. While after 12 weeks, Baker’s cysts were completely disappeared in 23 (54.8%) cases, most of the relapsed Baker’s cysts were complex Baker’s cysts. No side effects were reported in all cases.
Platelet Rich Plasma Therapy
PRP treatments are injections of blood platelets. The blood platelets come from you. A simple blood draw is taken. The blood is then spun or centrifuged to separate the blood’s platelets from the red cells. The collected platelets are then injected back into the knee to stimulate healing and regeneration. Platelets act as wound and injury healers. They are first on the scene at an injury, clotting to stop any bleeding and immediately helping to regenerate new tissue in the wounded area.
In February 2020 (6) doctors examined the effect of Platelet Rich Plasma therapy on knee swelling. The reason, as mentioned above, that a Baker’s cyst forms is that there is degenerative damage to the knee. The knee then fills with synovial fluid to protect itself. Synovitis, the inflammation of the synovial lining of the knee develops during the progression of osteoarthritis, which causes symptoms such as pain and swelling of the joints. The doctors of this study suggested that Platelet-rich plasma (PRP) can release quantities of growth factors and cytokines to act as anti-inflammatory, but to also rebuild the damaged soft tissue of the knee responsible for the patient’s knee instability and degenerative condition. In this animal study researchers found that “PRP can effectively alleviate the synovitis caused by osteoarthritis following loss of joint stability. Given the autologous origin, its low cost and low risk features of PRP, it’s a promising choice for osteoarthritis patients to control the symptoms caused by synovitis.”
A 29-year old male basketball player treated with PRP.
A 29-year old male basketball player treated with PRP. In this case history described by doctors at the Baylor College of Medicine, (5) a patient described a two-month history of right knee pain, 17 months after undergoing right knee anterior cruciate ligament reconstruction surgery. Upon examination there was medial joint line and medial collateral ligament tenderness with posterior knee swelling. After aspiration, a corticosteroid injection was administered with temporary symptom relief. Diagnostic ultrasound examination confirmed the Baker’s cyst. The patient then underwent two platelet-rich plasma injections into his right knee. Results: The patient reported complete resolution of pain and cyst size.
1 Saylik M, Gokkus K, Sahin MS. Factors affecting Baker cyst volume, with emphasis on cartilage lesion degree and effusion in the young and middle-aged population. BMC Musculoskeletal Disorders. 2021 Dec;22(1):1-1.
2 Fredericksen K, Kiel J. Bedside ultrasound‐guided aspiration and corticosteroid injection of a baker’s cyst in a patient with osteoarthritis and recurrent knee pain. Journal of the American College of Emergency Physicians Open. 2021 Apr;2(2):e12424.
3 Abate M, Di Carlo L, Di Iorio A, Salini V. Baker’s Cyst with Knee Osteoarthritis: Clinical and Therapeutic Implications. Medical Principles and Practice. 2021 Dec;30(5):401-7.
4 Mortada M, Amer YA, Zaghlol RS. Efficacy and Safety of Musculoskeletal Ultrasound Guided Aspiration and Intra-Lesional Corticosteroids Injection of Ruptured Baker’s Cyst: A Retrospective Observational Study. Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders. 2020 Nov;13:1179544120967383.
5 Song B, Yeh PC, Jayaram P. Leukocyte-rich platelet-rich plasma application in post-traumatic osteoarthritis with popliteal cyst: a case report. Regenerative Medicine. 2020 Jun;15(6):1695-702.
6 Yin J, Xu Z, Liu J. Alleviation of synovitis caused by joint instability with application of platelet-rich plasma. Thrombosis Research. 2020 Feb 1;186:20-5.